LU-56 lnet: multiple cleanups for inspection

LU-56 lnet: multiple cleanups for inspection

This patch covered multiple cleanups for previous patches:
- user "features" to replace "versions" of router checker ping
- code cleanup for lnet_ni_alloc
- fix a loading issue on 32-bit system
- comments cleanup and some small changes
- coding style cleanup

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: I96e5fa260d93082851c5146883df1a5b8a96ef42
Reviewed-on: http://review.whamcloud.com/3180
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>